Error in Naming the 1912-1942 Marriage Index

Screenshot from Ancestry's "Cook County, Illinois Marriage Indexes, 1912-1942

I am updating my website to reflect changes in record availability and, let me tell you, with Chicago research, knowing what's what is NEVER easy.

Ancestry offers a database titled Cook County, Illinois Marriage Indexes, 1912-1942.

I did a quick study, searching for exact years from 1912-1925, and noted the number of matches below. It's likely this index only covers 1914-1923 in a reliable way.

Some of the outlying entries may be correct. I find Thomas Kelly and Geneveve Carter listed in this index and in FamilySearch's Illinois, Cook County Marriages, 1871-1920 with the same year (1913) and license number.

But some are due to error. Max Stone and Mabel Freed come up under 1912, but the printed index page that's linked from the index entry says 1917 and it's corroborated by the FamilySearch index. The fiche was scratched, making the date hard to read.

I need to get to a Family History Center so I can do a bit more detective work, and I never say never, but a few words of advice:

1) If you're searching for a record through1920, use the FamilySearch index linked above.

2) If you're going to use this index to search for records outside of the 1914-1923 range, be cautious not to jump to the wrong conclusion if no matching entry can be found.

I'll try to address indexes for 1925 forward in another post.

Calculating Birth Date Ranges

In my last post, Visualizing Birth Evidence, I used date ranges calculated from an age on a particular date. It took me a long time to wrap my mind around this but now that I understand how it works, I find it much more useful than just subtracting an age from a year and it isn't that much harder to do.

Let's use Frank M. Smith as an example. On 2 July 1885, he stated, under oath, that he was forty-eight years old. [1]

Subtracting 48 from 1885, I get 1837. (To easily do this in my head, I subtract 40 from 1885 and get 1845. Then, because I can't take 8 from 5, I take 8 from 15 and get 7 and just reduce the 10s by 1 to get 38 instead of 48. And, I try to remember to add things back up to double-check my mental math.)

So, if 2 July 1885 happened to be Frank's birthday, he would have been born on 2 July 1837.

And, in fact, if he had been born any time between 1 January 1837 and 2 July 1837, he would have already turn 48 by 2 July 1885.

But what if he happened to have been born in the second half of the year?

If he was 48 on July 2, looking forward to celebrating his 49th birthday between 3 July 1885 and 31 December 1885, that would mean he was born in 1836.

So, the birth date range for Frank, who was 48 on 2 July 1885 is 3 July 1836 to 2 July 1837.

Let's do one more example.

When Frank registered to vote on 16 October 1888, he stated that he had been in the city of Chicago for 52 years. [2] He was born there, so, theoretically, that would have been  his age.

1888 minus 52 equals 1836. So, the date range for Frank's birth calculates to 17 October 1835 to 16 October 1836.

Now let's look at these two date ranges together.

1835												1836												1837
1	2	3	4	5	6	7	8	9	10	11	12	1	2	3	4	5	6	7	8	9	10	11	12	1	2	3	4	5	6	7	8	9	10	11	12
																		Proof of Heirship
									1888 Voter Registration
																					Published Family History

If -- and that's a big if -- Frank's age was stated correctly on the two dates, then comparing the two narrows his birthdate to between July 1836 and October 1836. Knowing that makes it easy to see that the exact birth date stated in a published family history falls squarely into the range of possibility. [3]

Some thing to keep in mind:

1) The approach is only as good as the information it's based on.

2) Date ranges are particularly useful for comparing age information from records that were created in different months.

3) When calculating date ranges from census records, the census dates vary, depending on the census year. (For a quick reminder, just Google "u s census dates.") Also, census takers might have recorded ages as of the census date or as of the date they visited--no matter what the instructions asked them to do.

And where can we find age information for particular dates in Chicago records?

Quickly brainstorming, let's see ...

• marriage licenses
• parent information on children's birth records
• death certificates
• voter registration (if the person was born in Chicago)
• proof of heirship interviews in probate files
• census records
• legal documents

What have I forgotten? Leave a note in the comment section to let us know!

So, in summary, here's the way that I've finally wrapped my mind around the idea of calculating birth date ranges from an age on a particular month, day, and year:

Subtract the age from the particular year to get the latest year. The latest date is the particular month and day with the latest year.

Subtract 1 from the latest year to get the earliest year.

The earliest date is the day after the particular month and day with the earliest year. 
__________

1.     Cook County, Illinois, probate file no. 4-2790 (1885), Marcia M. Smith, proof of heirship, 2 July 1885; Cook County Circuit Court Archives, Chicago.

2.     "Chicago, Illinois, Voter Registration, 1888," database with images, Ancestry (https://search.ancestry.com/search/db.aspx?dbid=5991 : accessed 5 November 2018), entry for Frank M. Smith born in Illinois.

3.     American Ancestry: Giving the Name and Descent, in the Male Line, of Americans Whose Ancestors Settled in the United States Previous to the Declaration of Independence, A. D. 1776, Vol. IX (Albany, N.Y.: Joel Munsell’s Sons, 1894), 132; digital image, Google Books (https://books.google.com/books?id=7Ew7AQAAIAAJ : accessed 5 November 2018).